This invention generally relates to a centralized monitor system for motor vehicles, and more particularly to an improved coupling arrangement between abnormality-detecting sensors and associated switching circuits to be employed in the monitor system.
In motor vehicles such as automobiles, as commonly accepted, it is highly effective for safety assurance that essential parts or objects incorporated in the automobile be monitored of abnormal operating conditions occurring thereat. By way of example, such parts or objects to be monitored include the functionings of various display lamps, battery capacities, quantities of various fluid consumables in store e.g. engine oil, window-water, coolant, etc., and wearings of brake lining elements, etc. In this connection, there has been known a centralized monitor system for automobiles of the type by which a car driver, as seated, may check up instantly those various items to be monitored.
This monitor system usually includes a plurality of monitor channels, each channel having a sensor for detection of abnormalities occurring at a respective part or object to be monitored, a switching circuit connected to the sensor and a warning display means e.g. a lamp connected to the switching circuit. Each sensor to be applied adjacent and in operative association with the respective part or object to be monitored, is usually in the form of a switch of the functional type which is to be made "on" when the object remains normal while being made "off" in response to the occurrence of abnormalities thereat. All the warning display lamps are usually conveniently panelled on an overhead console in the car.
With this arrangement, therefore, if any one part or object to be monitored shows abnormal or prohibitive operating conditions, the respective sensor becomes "off" in position, the switching circuit "on", so that the respective lamp is lit up to draw the attention of a car driver on that problem part or object.
However, this ordinary monitor system has had the problem in checking up if or not the switching circuits and lamps are damaged or fail. Namely, such checking procedure is that all of the individual sensors located differently within the vehicle structure are disconnected from the respective switching circuits so that the switching circuits now assume "on" positions as if they normally did so when the sensor was made "off" in response to the occurrence of abnormalities. If any warning display lamp still then is not lit up, it will be obvious that either a switching circuit or lamp in that monitor channel is damaged or fails. This procedure has been very troublesome and time-consuming because of the sensors being so differently located in the vehicle structure, despite the fact that frequent inspection of electric circuits or parts is very important to the monitor system.